Fan apparatus

ABSTRACT

There is provided a fan apparatus having a high-strength structure for supporting an impeller and a motor with good air quantity characteristics. The fan apparatus has a motor, an impeller, a motor base portion, a frame and a plurality of spoke portions. The impeller has a plurality of blades and are arranged to be rotated by the motor. The motor base portion supports the motor. The frame has an annular inner peripheral wall formed to surround the impeller as viewed from a rotation axis direction. The spoke portions connect the motor base portion and the frame. An end portion of the blade in the side of the frame is inside the inner peripheral wall and a blade portion having a length not less than half the length of the blade in the rotation axis direction is exposed, as viewed from a direction perpendicular to the rotation axis direction.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Japanese Patent Application No. 2016-194408, filed Sep. 30, 2016, which is hereby incorporated by reference in its entirety.

BACKGROUND Technical Field

The present disclosure relates to a fan apparatus and, more particularly, to a fan apparatus not provided with an air channel portion surrounding a whole of an outer peripheral portion of an impeller.

Background

Fan apparatuses are widely used as air blowers for cooling, ventilation, and air conditioning of household electrical appliances, office automation equipment, and industrial equipment, and vehicular air conditioning and air blowing. For example, a fan apparatus is attached to a heat-generating component, such as an MPU (micro processing unit) of an electronic apparatus, and used to improve cooling capability of a heat sink.

Japanese Patent Laid-Open No. 2001-304188 describes a cooling fan having a structure without a casing portion surrounding an impeller, to save both space and weight.

Japanese Patent Laid-Open No. 2002-159155 describes a structure of a fan motor with a heat sink configured such that the heat sink is attached to a fan.

Japanese Patent Laid-Open No. 2014-056792 describes a structure using a heat radiating unit including a heat sink and a fan as an air blowing apparatus to release heat generated by a light-emitting element in a lighting fixture to be mounted on a vehicle. The fan is stored in a storage portion provided in the heat sink.

SUMMARY

In the cooling fan illustrated in Japanese Patent Laid-Open No. 2001-304188, a motor attaching portion in a circular shape having a plurality of spoke portions is provided at a central portion of an impeller. If the spoke portions have large width dimensions, ventilation resistance when the cooling fan is driven is largely affected, and air quantity characteristics of the cooling fan deteriorates. To enhance the characteristics of the cooling fan, the width of each spoke portion needs to be set as small. For this reason, strength of the spoke portion tends to be low. The spoke portions are highly likely to break at the time of, for example, attaching the cooling fan to a piece of equipment or the like.

A solution to the above-described problem is not disclosed in Japanese Patent Laid-Open No. 2002-159155 and No. 2014-056792.

It is an object of the present disclosure to solve the above-described problem and to provide a fan apparatus having a high-strength structure for supporting an impeller and a motor with good air quantity characteristics.

In accordance with one aspect of the present disclosure, a fan apparatus includes a motor base portion, a motor arranged on an upper side of the motor base portion, an impeller having a plurality of blades and arranged to be rotated by the motor, a frame having an annular inner peripheral wall formed to surround the impeller as viewed from a rotation axis direction, and a plurality of spoke portions connecting the motor base portion and the frame. A lower end portion of each of the blades is inside the inner peripheral wall, and a blade portion having a length not less than half the length of the blade in the rotation axis direction is exposed, as viewed from a direction perpendicular to the rotation axis direction.

Preferably, a value obtained by dividing a distance between an upper end portion of the inner peripheral wall and the lower end portion of the blade by a dimension of the frame in a vertical direction is not less than 0.35, and the lower end portion of the blade is above a position in contact with the spoke portion.

The present disclosure allows provision of a fan apparatus having a high-strength structure for supporting an impeller and a motor with good air quantity characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a fan apparatus according to one embodiment of the present disclosure.

FIG. 2 is a view of the fan apparatus as viewed from an upper surface side.

FIG. 3 is a cross-sectional view taken along line A-A in FIG. 2.

FIG. 4 is a view of the fan apparatus as viewed from a lower surface side.

FIG. 5 is a side view of the fan apparatus.

FIG. 6 is a graph showing a positional relationship between a frame and a blade.

FIG. 7 is a graph showing results of measuring P-Q characteristics of the fan apparatus.

FIG. 8 is a graph showing results of measuring the P-Q characteristics of the fan apparatus.

DETAILED DESCRIPTION

A fan apparatus according to an embodiment of the present disclosure will be described below.

The fan apparatus is, for example, an axial fan having an impeller rotating about a rotation axis and a motor arranged with the impeller along the rotation axis. The fan apparatus does not have an air channel portion surrounding a whole side peripheral portion of the impeller and has a support structure in the shape of a plate. The support structure comprises a motor base portion supporting the motor and the motor base portion is joined to a surrounding frame via a plurality of spoke portions. The support structure is attached to a housing or the like of a different apparatus, and the fan apparatus is used for air blowing or the like in the apparatus.

In the description below, a direction about the rotation axis may be referred to as a circumferential direction, and a direction toward and away from the rotation axis may be referred to as a radial direction. A rotation axis direction may be referred to as a vertical direction. A direction from the motor toward the impeller along the rotation axis direction may be referred to as up (upward), and the opposite direction may be referred to as down (downward). Note that the terms “up” and “down” here are expressions with a focus only on the fan apparatus itself and are not expressions relating to a posture of the fan apparatus attached to the different apparatus.

Embodiment

FIG. 1 is a perspective view showing a fan apparatus 1 according to one embodiment of the present disclosure. FIG. 2 is a view of the fan apparatus 1 as viewed from an upper surface side. FIG. 3 is a cross-sectional view taken along line A-A in FIG. 2. FIG. 4 is a view of the fan apparatus 1 as viewed from a lower surface side. FIG. 5 is a side view of the fan apparatus 1.

For illustrative purposes, spoke portions 10 of a support member 2 are not shown in FIG. 2. An impeller 3 is not shown in FIG. 4.

As shown in FIG. 1, the fan apparatus 1 is an axial fan. The fan apparatus 1 has a motor 100, the support member 2, and the impeller 3.

The impeller 3 has a hub 4 and a plurality of blades 5. The hub 4 has a generally cylindrical shape. The hub 4 is connected to the motor 100. The plurality of blades 5 are attached to an outer peripheral surface of the hub 4. The hub 4 and the blades 5 are integrally molded through injection molding using resin. Note that the present disclosure is not limited to this and a whole or a part of each portion may be molded separately from a different portion. The hub 4 and the blades 5 may not be made of resin and may be made using a different material. The number of blades 5 is, for example, 9 and is not limited to this.

The fan apparatus 1 is configured to, for example, rotate the impeller 3 with the motor 100 such that gas, such as air, flows upward. Note that the fan apparatus 1 may be configured such that gas flows downward.

As shown in FIG. 2, the blades 5 are arranged at generally equal intervals (40°) in a circumferential direction. The plurality of blades 5 have shapes identical to each other.

The support member 2 has a frame 9, a motor base portion 6, two attaching portions 7 and 8, and the spoke portions 10 (10 a to 10 d).

The frame 9, the motor base portion 6, the attaching portions 7 and 8, and the spoke portions 10 are a one-piece molded article integrally molded through injection molding using resin. Note that the present disclosure is not limited to this and that a whole or a part of each portion may be molded separately from a different portion. The portions may not be made of resin but may be made using a different material.

The support member 2 is formed in the shape of a plate as a whole. In the present embodiment, the support member 2 is configured such that a dimension (thickness) of each portion in a vertical direction is identical to or smaller than a thickness of the frame 9. The support member 2 may be formed by machining a plate-like resin plate.

As shown in FIG. 4, the motor base portion 6 has four spoke portions 10. Each spoke portion 10 is arranged to have one end joined to the motor base portion 6 and the other end joined to the frame 9 such that the longitudinal direction of the spoke portion 10 is aligned with the radial direction. The spoke portions 10 connect the frame 9 and the motor base portion 6, thereby supporting the motor base portion 6 with respect to the frame 9.

As shown in FIG. 2, the frame 9 is formed in an annular shape in top view to surround an entire side peripheral portion of the impeller 3. That is, the frame 9 has an annular inner peripheral wall 9 a surrounding the impeller 3 as viewed from the rotation axis direction. The majority portion of the frame 9 is located on a lower side of the impeller 3. Actually, as shown in FIG. 5, a central portion in the vertical direction of the side peripheral portion of the impeller 3 is not surrounded by the frame 9 and is exposed (exposed in the radial direction) as viewed from a lateral side (in a direction perpendicular to a rotation axis).

As shown in FIG. 4, the attaching portions 7 and 8 are formed at respective opposing positions outside the annular frame 9. Each of the attaching portions 7 and 8 forms an earlike shape projecting partially from the frame 9 in the radial direction. Through-holes 7 a and 8 a are formed in the respective attaching portions 7 and 8. The attaching portions 7 and 8 are intended to attach the fan apparatus 1 to a housing of an equipment or a heat sink. That is, the attaching portions 7 and 8 can be fixed to a housing of a piece of equipment or the like by inserting bolts or screws into the through-holes 7 a and 8 a and tightening the bolts or screws.

Note that a lead wire 25 is wired to one spoke portion 10 d of the four spoke portions 10 along the spoke portion 10 d. The lead wire 25 is intended to supply power to the motor 100.

As shown in FIG. 4, the annular frame 9 and the spoke portions 10 have a shape generally symmetrical with respect to line B passing through centers of the through-holes 7 a and 8 a formed in the respective attaching portions 7 and 8, as viewed from the rotation axis direction (viewed from below). Note that only the spoke portion 10 d, the lead wire 25 being wired to the spoke portion 10 d, is different in shape from the other spoke portions 10 a, 10 b, and 10 c.

The lead wire 25 is electrically connected to a terminal portion of a circuit board 20 of the motor 100 (to be described later). The lead wire 25 is sheathed with a tube 26 and protected. The lead wire 25 is put on a hook 27 molded integrally with the annular frame 9 and is led out to outside the fan apparatus 1.

The motor 100 is a brushless DC motor of an outer rotor type. As shown in FIG. 3, the motor 100 is mounted to the motor base portion 6. The motor 100 has a rotor 12 and a stator portion 102.

The stator portion 102 has a bearing holder 16, bearings 21 and 22, and a stator 11. The stator 11 has a stator core 17, an insulator 18 (an upper insulator 18 a and a lower insulator 18 b), and coils 19.

The bearing holder 16 is fixed to the motor base portion 6 while being fit in an opening of a projecting portion 6 b formed to project upward at a center of the motor base portion 6. The stator 11 is attached to an outer peripheral surface of the bearing holder 16.

The stator 11 has the stator core 17 mounted while being fit on an outer periphery of the bearing holder 16, the upper insulator 18 a mounted to the stator core 17 from above, the lower insulator 18 b mounted to the stator core 17 from below, and the coils 19.

The stator core 17 is composed of a predetermined number of cores, each having a plurality of salient poles extending radially outward from an annular yoke portion, stacked in the rotation axis direction. The insulator 18 composed of the upper insulator 18 a and the lower insulator 18 b is mounted to the stator core 17. The coil 19 is attached to each of the salient poles of the stator core 17 while being wound around the salient pole via the insulator 18.

Note that the circuit board 20 populated with electronic components is mounted to an outer peripheral portion of the bearing holder 16 on a lower side of the lower insulator 18 b. The circuit board 20 is connected to the lead wire 25.

The rotor 12 has a rotor yoke 13, a magnet 14, and a shaft 15.

The rotor yoke 13 is a member in a cup shape opening downward made of a soft magnetic material, such as iron. The magnet 14 has a ring shape. The magnet 14 is fixedly attached to an inner peripheral surface of the rotor yoke 13. The shaft 15 is made of, for example, iron. The shaft 15 is attached to an upper surface of the rotor yoke 13 to project downward. The shaft 15 is coupled to the rotor yoke 13 while an upper end portion of the shaft 15 is pressed in a projecting portion 13 b formed at a center of the rotor yoke 13. The projecting portion 13 b of the rotor yoke 13 is formed through drawing.

The hub 4 of the impeller 3 is fixed to an outer peripheral surface of the rotor yoke 13. For example, the hub 4 is bonded using an adhesive. Note that the rotor yoke 13 may be formed through insert molding and that the impeller 3 including the rotor yoke 13 may be manufactured.

There is no resin on the upper surface (top surface) of the rotor yoke 13 and therefore, the rotor yoke 13 made of metal is exposed upward. With this configuration, a height in the vertical direction (rotation axis direction) of the fan apparatus 1 can be reduced by an amount corresponding to resin of the hub 4, and the fan apparatus 1 can be thinned. Additionally, since the rotor yoke 13 is exposed, heat inside the motor 100 is likely to be released to the outside through the rotor yoke 13, and stable operation can be expected.

As shown in FIG. 3, in the present embodiment, a part (a lower end portion) of each blade 5 is stored inside the frame 9 (stored inside the inner peripheral wall 9 a of the frame 9) and hidden by the frame 9 in side view. In other words, a dimension L of the frame 9 in the vertical direction is set such that the lower end portion of each blade 5 is stored inside the frame 9.

As described above, the fan apparatus 1 does not include an air channel portion surrounding the impeller 3 in a circumferential direction over an entire length of the impeller 3 in the vertical direction. In other words, in the fan apparatus 1, only a part of a lower end portion of the impeller 3 is hidden by the frame 9 in side view, and a portion having a length not less than half the length of the impeller 3 in the vertical direction is exposed in the radial direction in side view. That is, a dimension of each spoke portion 10 in the vertical direction can be increased and therefore, even if a width dimension of the spoke portion 10 as viewed from below is reduced, high rigidity and strength are ensured. Under the condition that the width dimension of each spoke portion 10 remains the same, the spoke portion 10 has higher rigidity and strength. Thus, the support member 2 supporting the impeller 3 and the motor 100 can be made higher in strength and less prone to breakage. The spoke portion 10 is connected to the frame 9 having a diameter larger than an outer diameter of the impeller 3 and therefore, as compared with a fan apparatus having only spoke portions as described in, for example, Japanese Patent Laid-Open No. 2001-304188, the rigidity and strength of the spoke portion 10 can be improved.

[Concerning Air Quantity Characteristics (P-Q Characteristics) of Fan Apparatus 1]

A positional relationship between the annular frame 9 as described above and the blade 5 of the impeller 3 was examined. Specifically, assuming that a displacement amount X is zero when the lower end portion of the blade 5 is at a position in contact with an upper end portion of the annular frame 9 (i.e., an upper end portion of the inner peripheral wall 9 a), that the displacement amount X is a plus when the lower end of the blade 5 is below the upper end portion of the annular frame 9 (at a position inside the annular frame 9), and that the displacement amount X is a minus when the lower end of the blade 5 is above the upper end portion of the annular frame 9 (at a position outside the annular frame 9), the ratio X/L of the displacement amount X (in millimeters) to the frame dimension L (in millimeters) is expressed. A dimension of the spoke portion 10 is denoted by Y (in millimeters). In FIG. 3, the displacement amount X, the frame dimension L, and the thickness dimension Y of the spoke portion 10 are shown.

A maximum static pressure (Pa) and a maximum air quantity (m³/min) of the fan apparatus 1 at a position corresponding to the lower end portion of the blade 5 were measured in the case of forward rotation of the impeller 3. Air quantity characteristics (P-Q characteristics) at respective positions were also measured.

FIG. 6 is a graph showing the positional relationship between the frame 9 and the blade 5.

Results of measuring the characteristics at the respective positions (positions with values of −0.31, −0.07, 0.35, 0.45, and 0.55 of X/L) are shown in FIG. 6. The abscissa represents the ratio (X/L) of the lower end portion of the blade 5. Note that forward rotation of the impeller 3 is rotation in a direction with the spoke portion 10 side as an air suction opening and the impeller 3 side as an air discharge opening.

FIG. 6 shows a tendency for the maximum air quantity (legend symbol: black square) to increase as the lower end portion of the blade 5 comes from the upper end of the annular frame 9 to a lower side (a position inside the annular frame 9) and increase greatly since a position with a value of about 0.35 of X/L. Similarly, the maximum static pressure (legend symbol: white circle) increases, peaks when X/L is within the range of about 0.35 to 0.55, and exhibits a maximum value at a position with a value of about 0.45 of X/L. For this reason, a position within the range of about 0.35 to 0.55 is preferable as a position of the lower end portion of the blade 5 lower than the upper end portion of the annular frame 9 (a position inside the frame 9 in the annular shape). An upper limit for the position is a position in contact with the spoke portion 10. Thus, the upper limit is less than (L-Y).

FIGS. 7 and 8 are graphs showing results of measuring P-Q characteristics of the fan apparatus 1.

FIGS. 7 and 8 show results of measuring P-Q characteristics of the fan apparatus at respective positions with five values of X/L shown in FIG. 6. FIG. 7 shows P-Q characteristics when X/L is about −0.31 (legend symbol: white square), when X/L is about −0.07 (legend symbol: black square), and when X/L is about 0.35 (legend symbol: white circle). FIG. 8 shows P-Q characteristics when X/L is about 0.35 (legend symbol: white circle), when X/L is about 0.45 (legend symbol: black square), and when X/L is about 0.55 (legend symbol: white square).

As can be seen from FIGS. 7 and 8, the P-Q characteristics are improved as the lower end portion of the blade 5 comes from the upper end portion of the annular frame 9 to a lower side (a position inside the frame 9 in the annular shape). When X/L is about 0.45 and when X/L is about 0.55, a tendency for static pressure characteristics to decrease particularly in a middle range is improved.

[Others]

The shape of the support member is not limited to the above-described one. For example, the number of attaching portions is not limited to two. More than two attaching portions may be provided or only one attaching portion may be provided.

A motor may be of an inner rotor type.

The above-described embodiment is to be considered as illustrative in all respects and not limitative. The scope of the present disclosure is defined not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all changes within the scope. 

What is claimed is:
 1. A fan apparatus comprising: a motor base portion; a motor arranged on an upper side of the motor base portion; an impeller having a plurality of blades and arranged to be rotated by the motor; a frame having an annular inner peripheral wall formed to surround the impeller as viewed from a rotation axis direction; and a plurality of spoke portions connecting the motor base portion and the frame, wherein a lower end portion of each of the blades is inside the inner peripheral wall, and a blade portion having a length not less than half the length of the blade in the rotation axis direction is exposed, as viewed from a direction perpendicular to the rotation axis direction.
 2. The fan apparatus according to claim 1, wherein a value obtained by dividing a distance between an upper end portion of the inner peripheral wall and the lower end portion of the blade by a dimension of the frame in a vertical direction is not less than 0.35, and the lower end portion of the blade is above a position in contact with the spoke portion. 